Starting from stratification of alternating thin films of Si and ZnO produced by sputtering technique, followed by an annealing process at a sufficiently low temperature (560 °C) under vacuum (10–4 mbar), we were able to form crystalline nano‐aggregates of Si and ZnO in a dielectric matrix of zinc silicate and silicon oxide. The grain size of the Si crystallites depended on the Si/ZnO ratio in the starting material and on the annealing duration. Materials with tuned band gaps have been produced (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)